1. Field of the Invention
The present invention relates to a scan driver for a flat panel display (FPD) and, more particularly, to a scan driver and organic light emitting display (OLED) that selectively perform progressive scanning and interlaced scanning.
2. Discussion of the Background
A scan driver is a circuit in a flat panel display (FPD) that is used to drive a plurality of pixels arranged on a flat panel in rows and columns. The scan driver allows pixels arranged in a selected row to emit light by inputting data to the selected pixels.
In general, the formation of an image frame requires a vertical synchronous signal, which defines a period for displaying the image frame, and a horizontal synchronous signal, which selects respective lines of a plurality of pixel lines that form the image frame. While the horizontal synchronous signal is being activated, image data is input to pixels arranged in the line to which the horizontal synchronous signal is transmitted.
In a passive matrix (PM) display, pixels start to emit light at the same time that image data is input. However, in an active matrix (AM) display, when input image data is stored, pixels arranged in a line can emit light after a predetermined period of time.
In a liquid crystal display (LCD), an organic light emitting display (OLED), and a plasma display panel (PDP), the horizontal synchronous signal is referred to as a scan signal, and will be referred to as such hereinafter.
A circuit that transmits the scan signal to a panel in which pixels are arranged is a scan driver. Specifically, the scan driver transmits the scan signal to the lines along which rows of pixels are disposed. The selection and activation of the respective lines using the transmission of the scan signal may be typically performed in two manners: progressive scanning and interlaced scanning.
In the progressive scan method, a scan signal is sequentially transmitted to scan lines coupled with rows of pixels in a panel, beginning with the first row and sequentially proceeding to the last row.
In the interlaced scan method, a scan signal is first sequentially transmitted to all odd-numbered lines in a first process, and then the scan signal is sequentially transmitted to all even-numbered lines. Thus, through the first half of a frame display cycle, the odd-numbered lines receive the scan signal. Through the second half of a frame display cycle, the even-numbered lines receive the scan signal.
A conventional FPD performs either the progressive scan method or the interlaced scan method to display image data, but cannot selectively perform both methods.